Different types of springs and spring systems are commonly used as the reflexive core of seating and support products such as chairs and mattresses. A common spring system which is used in mattresses and some upholstered furniture is the so-called “innerspring” which can be in one form a plurality of similarly or identically formed springs which are interconnected in an array or matrix. An innerspring provides a distributed generally homogeneous reflexive support system to give underlying support to an expanse such as the sleep surface of a mattress. The uniform spring rate across the expanse results from the common configuration of each of the interconnected springs. Attempts to alter the spring rate and feel of an entire innerspring or support area of an innerspring involve the use of different types and amounts of materials such as foam, textiles and natural fibers as overlays on the innerspring. While the use of such materials does alter the feel and performance of the support system, it does not of course alter the spring rate of the underlying or internal innerspring.
Innersprings which are made of formed steel wire and are manufactured by wire forming machinery which forms the individual springs or coils, and then connects them together by smaller lacing wires or other fasteners. Once the machines are set up to make a particular spring or coil design and interconnection, large runs are made and it is difficult to change the form of the springs and innerspring. Therefore, with current innerspring production technology, it is not practical to produce a single innerspring which has variable or non-homogenous spring rates and support characteristics in different areas of the innerspring.